Any USB "charger" or power supply should be fine.
While it will definitely power it,I do it all the time. However, from my experience, you might want to remove batteries as it seems to continue to drain the batteries if left in.
+1. I've never seen an oddball voltage on a USB charger but checking never hurts anything. Ran my Pro-18 with an orphaned Samsung charger rated at 780 mA for a good long time, no issues whatsoever. I can't see that the TRX-1 would have radically different power consumption.Any USB "charger" or power supply should be fine.
I'd advise checking it supplies 5V (or 5.2V or similar figure just over 5V) and at least 500mA just in case you have an unusual USB phone charger.